MFJ MFJ-993 User manual

INSTRUCTION MANUAL
CAUTION: Read All Instructions Before Operating Equipment
MFJ ENTERPRISES, INC.
300 Industrial Park Road
Starkville, MS 39759 USA
Tel: [phone] Fax: [phone]
COPYRIGHT 2004 MFJ ENTERPRISES, INC.
C
Model MFJ-993
VERSION 1C
IntelliTuner
Automatic Antenna Tuner
TM

MFJ-993 IntelliTuner Automatic Antenna Tuner Instruction Manual
©2003-2004 MFJ Enterprises, Inc.
i
Contents
THE BASICS
Introduction...................................................................................................................................... 1
Features............................................................................................................................................ 2
Specifications................................................................................................................................... 2
Fast Start .......................................................................................................................................... 3
Front Panel....................................................................................................................................... 4
SWR/Wattmeter.................................................................................................................. 4
LCD Display ....................................................................................................................... 4
LCD Contrast Control......................................................................................................... 4
ANT Button ........................................................................................................................ 4
MODE Button.....................................................................................................................4
C-UP and C-DN Buttons .................................................................................................... 4
L-UP and L-DN Buttons..................................................................................................... 5
AUTO Button .....................................................................................................................5
TUNE Button...................................................................................................................... 5
VOL Control ....................................................................................................................... 5
POWER Button................................................................................................................... 5
Back Panel ....................................................................................................................................... 6
Power .................................................................................................................................. 6
Remote Port ........................................................................................................................ 6
Radio Interface.................................................................................................................... 6
Transmitter.......................................................................................................................... 7
Balanced Line ..................................................................................................................... 7
Wire .................................................................................................................................... 7
Ground ................................................................................................................................ 7
Antenna 1............................................................................................................................ 7
Antenna 2............................................................................................................................ 7
Installation ....................................................................................................................................... 8
SWR/Wattmeter............................................................................................................................... 8
THE MENUS
Main Mode Menus........................................................................................................................... 9
Digital Wattmeter Menu ..................................................................................................... 9
Power Bar Meter Menu..................................................................................................... 10
SWR Bar Meter Menu ...................................................................................................... 10
L-Network Menu .............................................................................................................. 10
Tuner Indicators............................................................................................................................. 13
Antenna............................................................................................................................. 13
Memory............................................................................................................................. 13
IntelliTune......................................................................................................................... 13
Auto/Semi ......................................................................................................................... 13
StickyTune........................................................................................................................ 13
SWR Beep......................................................................................................................... 13

MFJ-993 IntelliTuner Automatic Antenna Tuner Instruction Manual
©2003-2004 MFJ Enterprises, Inc.
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LC Limit ........................................................................................................................... 13
Meter Range...................................................................................................................... 13
Setup Mode Menus ........................................................................................................................ 13
Target SWR Menu ............................................................................................................ 13
Auto Tune SWR Menu ..................................................................................................... 14
Meter Range Menu ........................................................................................................... 14
Memory Menu .................................................................................................................. 14
IntelliTune Menu .............................................................................................................. 15
SWR Beep Menu .............................................................................................................. 15
Beep Menu........................................................................................................................ 15
Peak Hold Menu ............................................................................................................... 15
Refresh Menu.................................................................................................................... 15
LC Limit Menu ................................................................................................................. 15
OPERATION
Manual Tuning............................................................................................................................... 16
Meter Codes and Audible Beeps.................................................................................................... 16
Grounding Hints ............................................................................................................................ 18
Antenna System Hints.................................................................................................................... 19
Location ............................................................................................................................ 19
Matching Problems ........................................................................................................... 19
APPENDICES
Resetting the Tuner........................................................................................................................ 21
Factory Defaults................................................................................................................ 21
Delete Antenna Memory................................................................................................... 22
Total Reset ........................................................................................................................ 22
Self Test ......................................................................................................................................... 22
Power Down Circuit Test............................................................................................................... 23
Relay Test ...................................................................................................................................... 24
Firmware Version Number via Meter............................................................................................ 24
Setting the Speaker Volume........................................................................................................... 24
Wattmeter Calibration.................................................................................................................... 25
SWR Bridge Calibration ................................................................................................................ 25
Frequency Counter Calibration...................................................................................................... 26
In Case of Difficulty ...................................................................................................................... 27
Technical Assistance...................................................................................................................... 27
List of Accessories......................................................................................................................... 27
Circuit Block Diagram................................................................................................................... 28
FIGURES
Figure 1. Installation Block Diagram.............................................................................................. 3
Figure 2. MFJ-993 Front Panel....................................................................................................... 4
Figure 3. MFJ-993 Back Panel ....................................................................................................... 6
Figure 4. Alinco Interface Cable..................................................................................................... 7
Figure 5. Icom Interface Cable ....................................................................................................... 7
Figure 6. SWR/Wattmeter .............................................................................................................. 8

MFJ-993 IntelliTuner Automatic Antenna Tuner Instruction Manual
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Figure 7. Power Bar Meter............................................................................................................ 10
Figure 8. SWR Bar Meter ............................................................................................................. 10
Figure 9. Mode Button Flow Chart and Button Action ................................................................ 11
Figure 10. Main Mode Menus Display ......................................................................................... 12
Figure 11. Power-On Operations .................................................................................................. 21
Figure 12. MFJ-993 Circuit Block Diagram................................................................................. 28
TABLES
Table 1. Memory Resolution ........................................................................................................ 14
Table 2. Meter Needle Stationary Codes ...................................................................................... 17
Table 3. Meter Needle Bounce Codes .......................................................................................... 18
Table 4. Failure Messages............................................................................................................. 23

MFJ-993 IntelliTuner Automatic Antenna Tuner Instruction Manual
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MFJ-993 IntelliTuner Automatic Antenna Tuner Instruction Manual
©2003-2004 MFJ Enterprises, Inc.
1
The Basics
Introduction
The MFJ-993 IntelliTunerTM lets you rapidly tune any antenna automatically: balanced, unbalanced, or
single-wire. The MFJ-993 is a comprehensive automatic antenna tuning center with SWR/wattmeter,
antenna switch for two antennas, and a 4:1 current balun for balanced lines.
MFJ's exclusive InstantRecallTM, IntelliTuneTM and AdaptiveSearchTM algorithms give you fast automatic
tuning with more than 2000 non-volatile memories.
The tuner includes a highly efficient switching L-network with wide matching capability, 1.8 to 30 MHz
coverage, cross-needle power meters, backlight LCD display, a port for an accessory remote control, a
radio interface port, and heavy-duty 16 amp/1000 volt relays. It is rated at 300 watts PEP SSB and 150
watts CW.
A maximum of 256 values of capacitance and 256 values of inductance are available. With the
inductance switched between the input and output side, this provides a total of 131,072 L/C tuning
combinations. The nominal tuning ranges are 0 to 3900 pF and 0 to 24 µH.
All MFJ IntelliTunersTM learn and remember. When you transmit, they automatically adjust for minimum
SWR and remember the frequency and tuner settings, safely stored in non-volatile memory. The next
time you operate on that frequency (or close to it) and antenna, these tuner settings are instantly restored
and you’re ready to operate in milliseconds. Each of two antenna selections can learn and remember
more than a thousand frequencies and tuner settings.
When you key your transmitter, MFJ’s InstantRecallTM checks its memory to see if you have operated that
frequency before. If so, tuning is instantaneous and you’re ready to operate. If not, MFJ’s IntelliTuneTM
algorithm (based on MFJ’s famous SWR Analyzer technology) kicks in. It measures the complex
impedance of your antenna. Next, it calculates the components it needs and instantly snaps them in.
Finally, it fine-tunes to minimize SWR, and you’re ready to operate--all in a fraction of a second.
If the antenna impedance is not within the tuner’s measurement range, MFJ’s AdaptiveSearchTM
algorithm goes into action. Frequency is measured and relevant components values are determined. Only
those values are searched for fast tuning. If it still cannot find a match, the search is performed again
using a different search pattern.
The target SWR can be set at 1.0 through 2.0. The minimum power to tune is approximately five watts.
You can manually tune where you can’t transmit (for listening out of ham bands).
The optional MFJ-993RC Remote Control provides most tuner controls, allowing convenient remote
locating of the tuner itself.
All MFJ’s IntelliTunersTM support radio tuner interfaces that are compatible with Icom AH-3 and AH-4
tuners and Alinco EDX-2 tuner. Optional interface cables MFJ-5124A (for Alinco) and MFJ-5124I (for
Icom) are available from MFJ Enterprises, Inc. Interface cables for compatible Kenwood and Yaesu
radios will be available in the future.
The tuners enter a “sleep” mode when idle and when no transmit signal is present, turning off the
microprocessor clock to avoid the generation of spurious signals.

MFJ-993 IntelliTuner Automatic Antenna Tuner Instruction Manual
©2003-2004 MFJ Enterprises, Inc.
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Features
• Automatically matches antennas from 6 to 1600 ohms impedance
• Handles 300 watts PEP SSB, 150 watts CW
• Tune in less than 15 seconds, usually less than 5 seconds
• Over 2000 non-volatile memories for tuner settings
• Highly efficient switching L-network matching circuit
• 1.8 to 30 MHz continuous frequency coverage
• Adjustable target SWR 1.0 to 2.0
• Adjustable SWR threshold 0.5 to 1.5
• Lighted cross-needle SWR/wattmeter with high, low, and auto range options
• Multifunction backlit LCD display with contrast control
• Built-in frequency counter
• Numeric readings for SWR, forward and reflected power
• Bar meters for SWR, forward and reflected power
• Aural SWR meter with volume control
• Two SO-239 coax fed antenna connectors
• Connector for random wire or single wire antennas
• Built-in 4:1 current balun for balanced line antennas
• Optional remote control
• Optional radio interface for compatible radios
Specifications
• Impedance matching range: 6 to 1600 ohms
• Minimum power for tuning: 5 watts
• Maximum power while tuning: 100 watts with foldback, 20 watts without foldback
• RF power limit: 300 watts PEP SSB, 150 watts CW
• Frequency range: 1.8 to 30 MHz continuous coverage
• Frequency counter accuracy: ±1 kHz across HF bands
• Frequency counter range: up to 50 MHz
• Capacitance range: 0 to 3908 pF nominal (256 values)
• Inductance range: 0 to 24.86 µH nominal (256 values)
• Relay rating: 16 amp 1000 volts
• Relay electrical life: 100,000 operations
• Relay mechanical life: 10 million operations
• Memory endurance: 1 million write cycles
• Memory data retention: 100 years
• Power requirements: 12 - 15 volts DC, 2.1 × 5.5 mm coaxial plug, center pin positive
• Current consumption: 1 amp or less
• Dimensions (approx.): 10.1 × 2.8 × 9.2 in. (257 × 71 × 234 mm) (width/height/depth)
not including connectors
• Weight (approx.): 3.9 lb (1.77 kg)
† Specifications and design are subject to change without notice.

MFJ-993 IntelliTuner Automatic Antenna Tuner Instruction Manual
©2003-2004 MFJ Enterprises, Inc.
3
Fast Start
WARNING
●Never operate the tuner with its cover removed. Contact with the components inside the
tuner while transmitting will result in painful RF burns.
●Locate the tuner so that the rear terminals are not accessible during operation. The single
wire and balanced line connection may have high voltage while transmitting.
●Disconnect all antennas from the tuner during lightning storms.
●Always tune with low power (about 10 watts). Apply maximum power only after tuning up.
●Never exceed tuner specifications.
●Do not transmit with a high SWR for extended periods of time.
1. Connect the MFJ-993 to a 12-15 VDC voltage source capable of supplying at least 1 amp.
2. Connect your transmitter to the TRANSMITTER connector using a 50-ohm coaxial cable.
3. Connect your coax-fed antenna to the ANTENNA 1 connector using a 50-ohm coaxial cable, or
connect your random wire to the WIRE binding post, or connect your balanced line antenna to the
BALANCED LINE binding posts and connect a jumper between the other two posts as indicated.
4. Connect your ground connection to the GROUND post.
5. Press the [POWER] button to turn on the MFJ-993 tuner. Place the [ANT] button in the out position
to select antenna 1. Press the [AUTO] button in to select semi-automatic mode.
6. Key your transmitter to output a carrier of 10 watts CW, FM or AM.
7. Press and hold the [TUNE] button on the MFJ-993 for one second to start the automatic tuning
process. When completed, check to ensure an SWR of 2.0 or less before increasing RF power.
8. You are ready to transmit.
Note: During the automatic tuning process, the tuner will make some noise. These are the relays
switching at a very fast pace and it is normal operation. Do not be alarmed.
Note: When the tuner power is OFF, the tuner is in bypass mode and RF from the transmitter goes
directly to the antenna (ANTENNA 1) with no matching. When the tuner power is ON,
pressing [C-DN] and [L-DN] simultaneously or pressing [TUNE] quickly places the tuner in
bypass mode (zero inductance and zero capacitance) and indicates by the reflected needle
bouncing to 20 watts.
Transmitter MFJ-993
50-ohm Coax
Antenna 1
RF Ground 12 VD
C
Antenna 2
Figure 1. Installation Block Diagram.

MFJ-993 IntelliTuner Automatic Antenna Tuner Instruction Manual
©2003-2004 MFJ Enterprises, Inc.
4
Front Panel
0
10
30
50
100
200
300
0
5
20
40
60
8
5.0
3.0 2.0
1.5
1.2
Hi x1
Lo x.1
400-3083
1
10
MODEL
MFJ-993
ANT C-UP L-UP AUTO POWER
MODE C-DN L-DN TUNE
LCD
SWR
VOL
Z
AUTOMATIC ANTENNA TUNER
300 Watts PEP SSB / 150 Watts CW
BYPASS 300 / 30
WATTS
MFJ IntelliTuner
TM
11.2 1.5 235
SWR
14.100 MHz 1.1
FWD=100 REF=0.5
AUTO RANGE
0255075100
Pwr 300
Figure 2. MFJ-993 Front Panel.
• SWR/Wattmeter: The cross-needle meter measures forward power, reflected power, and SWR. It
operates whenever the tuner is power on. Full-scale readings are 300 watts forward and 60 watts
reflected. The meter can be set to low power range of 30 watts forward and 6 watts reflected. The
SWR is measured at the point where the two needles cross. See “SWR/Wattmeter” on page 8 for
more detailed information.
• LCD Display: A 2-line by 16-character alphanumeric display. It displays the tuner’s various menus
and status. The display contrast can be adjusted by the [LCD] control on the front panel. Below the
display are the SWR and power bar meter scales. Refer to Figure 10 for descriptions of the various
displayed information.
• LCD Contrast Control: A trimpot control that adjusts the contrast of the LCD display. Use a small
flat blade screwdriver and turn clockwise to increase contrast.
• ANT Button: Used to select the antenna to tune. Button out selects Antenna 1; button in selects
Antenna 2. The Antenna indicator on the main display indicates the selected antenna. A balanced
feedline or a single-wire antenna is, by default, Antenna 1. Changing the [ANT] button will switch
the antenna only when there is no RF power.
• MODE Button: Time-sensitive and used to navigate through the various main menus and to enter or
exit the setup menus.
• C-UP and C-DN Buttons: Used to manually increase or decrease the capacitance of the L-network
matching circuit. The capacitance range is 0 to 3908 pF (picofarads). The upper limit of capacitance,
dependent on frequency, is used to limit the maximum voltage and current across the tuner’s
components. This limit can be removed in the LC Limit setup menu, but is not recommended.
Note: Pressing [C-UP] and [C-DN] simultaneously toggles the capacitor between the input
and output sides of the L-network. Forward needle bounces to 30 watts when the
capacitor is on the transmitter side. Reflected needle bounces to 5 watts when the
capacitor is on the antenna side.

MFJ-993 IntelliTuner Automatic Antenna Tuner Instruction Manual
©2003-2004 MFJ Enterprises, Inc.
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• L-UP and L-DN Buttons: Used to manually increase or decrease the inductance of the L-network
matching circuit. The inductance range is 0 to 24.86 µH (microhenries). The upper limit of
inductance, dependent on frequency, is used to limit the maximum voltage and current across the
tuner’s components. This limit can be removed in the LC Limit setup menu, but is not recommended.
Shortcut: Press both [L-UP] and [L-DN] buttons simultaneously to toggle SWR Beep on and
off. See “SWR Beep Menu” on page 15.
Note: Pressing [C-DN] and [L-DN] (both DOWN buttons) simultaneously places the tuner in
bypass mode. The reflected needle bouncing to the 20-watt mark indicates this. RF from
the transmitter goes directly to the antenna with no matching.
• AUTO Button: Used to select automatic or semi-automatic tuning mode. Button out selects
automatic mode--the tuning routine is automatically started when at least 5 watts of power is applied
and the SWR is a preset amount above the preset target SWR. Button in selects the semi-automatic
mode--the tuning routine starts only when the [TUNE] button is pressed. The Auto/Semi indicator on
the main display indicates the selected mode.
Note: During the tuning process, the tuner will make some noise. These are the relays
switching at a very fast pace and it is normal operation. Do not be alarmed.
• TUNE Button: Has three different functions based on the length of time you press and hold it before
releasing. Press [TUNE] quickly (less than 0.5 second) to bypass the tuner. RF from the transmitter
goes directly to the antenna with no matching.
Press and hold [TUNE] for 0.5 to 2 seconds to start the automatic tuning process. The transmitter
must be keyed first with at least 5 watts of power. When the SWR is already below the target SWR,
pressing [TUNE] will fine-tune the match for a lower SWR, if possible.
“StickyTune” allows for one-handed tuning operation. Normal tuning requires keying the transmitter
with one hand and using the other hand to push the [TUNE] button to start the tuning process. To
toggle the StickyTune mode on and off, press and hold the [TUNE] button for two seconds. When
enabled, a bar appears on top of the Auto/Semi indicator, and the tuning process starts automatically
when the transmitter is keyed with at least 5 watts of power regardless of the SWR. This works in
both automatic and semi-automatic modes. One beep indicates on and two beeps indicate off.
• VOL Control: A trimpot control that adjusts the volume level of the aural SWR meter. Use a small
flat blade screwdriver and turn clockwise to increase volume level.
• POWER Button: Used to turn the power on and off. Note that during power-on the analog meter
bounces three times (to indicate the model number, 993). When the power is off, the tuner is placed
in bypass mode and Antenna 1 is selected. When turning on the power, the tuner automatically
restores all previous settings and displays the target SWR on the main screen.
WARNING: Do not turn the power on and off rapidly, otherwise the tuning setting
memory can be corrupted and the unit will have to be reset to factory defaults.
Note: When the tuner power is OFF, the tuner is in bypass mode and RF from the transmitter
goes directly to the antenna (ANTENNA 1) with no matching.

MFJ-993 IntelliTuner Automatic Antenna Tuner Instruction Manual
©2003-2004 MFJ Enterprises, Inc.
6
Back Panel
RADIO
INTERFACE
+
POWER
12VDC
1A
REMOTE
PORT
ANTENNA 1 ANTENNA 2
TRANSMITTER
BALANCED LINE
GROUND
WIRE
MFJ ENTERPRISES, INC.
STARKVILLE, MS USA
!
Do not connect WIRE and
ANTENNA 1 at same time!
Install Jumper When Using
BALANCED LINE Antenna
*
*
Figure 3. MFJ-993 Back Panel.
• Power: This jack accepts a standard 2.1 × 5.5 mm coaxial plug with positive center and negative
sleeve. The tuner requires 12 volts DC at up to 1 amp. The use of a regulated supply is not
mandatory but is recommended for best performance. An optional 12 volts DC 1.5 amp power
supply, the MFJ-1316, is available from MFJ Enterprises, Inc.
WARNING: Do not apply voltages greater than 18 volts to this unit, or permanent damage
to the unit may result.
Note: When the tuner power is OFF, the tuner is in bypass mode and RF from the transmitter
goes directly to the antenna (ANTENNA 1) with no matching.
• Remote Port: A female DB-9 connector for connecting to the MFJ-993RC Remote Control,
allowing remote operation of the tuner. The MFJ-993RC duplicates all the front panel buttons except
[POWER] and [MODE]. In addition, there are two LEDs on the remote control. The red Tuning
LED lights to indicate tuning is in progress and the green SWR LED lights when the SWR is below
the target SWR.
Note: To use the remote control, both the [ANT] and [AUTO] buttons on the automatic tuner
must be pressed in; otherwise, Antenna 1 and Automatic mode are selected.
• Radio Interface: A 3.5 mm stereo phone jack for connecting to the tuner interface connector of
compatible radios. The MFJ-993 should be powered on first (TURN ON RADIO will display and
both needles will bounce) and then the radio, so the radio knows a remote tuner is present.
The Radio Interface works with radios that are compatible with the Icom AH-3, Icom AH-4 and
Alinco EDX-2 tuners. When connected to a compatible radio, it enables the Tune button on the radio.
Pressing the Tune button on the radio causes the radio to temporarily switch to CW mode, transmit 10
watts and start the tuning process. Once the tuning process is completed, the tuner signals the radio
and the radio will return to the previous mode and power setting.
WARNING: Make sure the +13.8 volts connection on the radio’s tuner port is capable of
supplying at least 1 amp of current, since the MFJ-993 uses up to 1 amp.

MFJ-993 IntelliTuner Automatic Antenna Tuner Instruction Manual
©2003-2004 MFJ Enterprises, Inc.
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Interface cables for Alinco and Icom radios are available from MFJ Enterprises, Inc. Interface cables
for compatible Kenwood and Yaesu radios will be available in the future. The MFJ-5124A interface
cable provides power and control between an Alinco radio and the MFJ automatic tuner. Supported
Alinco radios are DX-70, DX-77, and any Alinco radio that supports the Alinco EDX-2 tuner.
Pin 3 (Key) connects to the Tip of 3.5 mm Stereo Phone Plug.
Pin 5 (Start) connects to the Ring of 3.5 mm Stereo Phone Plug.
Pin 2 (+13.8V) connects to the Center Pin of Power Plug.
Pin 1 (Ground) connects to the Sleeves of both 3.5 mm Stereo Phone Plug and Power Plug.
Pin 4 is not connected.
Figure 4. Alinco Interface Cable.
The MFJ-5124I interface cable provides power and control between an Icom radio and the MFJ
automatic tuner. Supported Icom radios are IC-706, IC-707, IC-718, IC-725, IC-728, IC-736, IC-738,
IC-746, IC-756, IC-765, IC-775, and any Icom radio that supports the Icom AH-3 and AH-4 tuners.
Push and hold the radio’s [TUNER] button for two seconds to start the tuning process. Push
[TUNER] quickly to bypass the tuner.
Pin 1 (Key) connects to the Tip of 3.5 mm Stereo Phone Plug.
Pin 2 (Start) connects to the Ring of 3.5 mm Stereo Phone Plug.
Pin 3 (+13.8V) connects to the Center Pin of Power Plug.
Pin 4 (Ground) connects to the Sleeves of both 3.5 mm Stereo Phone Plug and Power Plug.
Figure 5. Icom Interface Cable.
• Transmitter: SO-239 connector for coax cable from transmitter or transceiver.
• Balanced Line: Two binding posts for connecting balanced line antennas. To use balanced line
antenna, install a jumper as shown to the WIRE binding post.
• Wire: Binding post for connecting single wire antennas. Notice the WIRE binding post is internally
connected to the ANTENNA 1 connector.
Note: To use the WIRE binding post, make sure to remove the antenna, if any, from the
ANTENNA 1 connector.
• Ground: Wing-nut terminal for RF ground wire connection.
• Antenna 1: SO-239 connector for coax cable from antenna. Notice the ANTENNA 1 connector is
internally connected to the WIRE binding post.
Note: To use the ANTENNA 1 connector, make sure to remove the jumper and wire antenna, if
any, from the WIRE binding post.
• Antenna 2: SO-239 connector for coax cable from antenna.

MFJ-993 IntelliTuner Automatic Antenna Tuner Instruction Manual
©2003-2004 MFJ Enterprises, Inc.
8
Installation
WARNING
●Never operate the tuner with its cover removed. Contact with the components inside the
tuner while transmitting will result in painful RF burns.
●Locate the tuner so that the rear terminals are not accessible during operation. The single
wire and balanced line connection may have high voltage while transmitting.
●Disconnect all antennas from the tuner during lightning storms.
●Always tune with low power (about 10 watts). Apply maximum power only after tuning up.
●Never exceed tuner specifications.
●Do not transmit with a high SWR for extended periods of time.
1. Place the tuner in a convenient location at the operating position. With a random wire or balanced
line, the feed through insulators may have high RF voltages. These voltages can cause serious RF
burns if the terminals are touched when transmitting. Be sure to locate the tuner so these terminals
cannot accidentally be contacted during operation.
2. Install the tuner between the transmitter and the antenna. Use a 50-ohm coaxial cable (such as RG-
58) to connect the transmitter (or amplifier) to the connector marked TRANSMITTER on the rear of
the tuner. See Figure 1 on page 3.
3. Connect the antenna(s) to the tuner as follows:
• Coaxial feedlines to the SO-239 connectors labeled ANTENNA 1 and/or ANTENNA 2.
• Random wire or single wire line antennas should be connected to the WIRE binding post on the
back of the tuner (and remove the jumper wire). Note the back panel warning: Do not connect
WIRE and ANTENNA 1 at same time! When a single wire antenna is connected it “becomes”
ANTENNA 1.
Note: Route all single and random wire antennas safely to prevent RF burn hazard.
• For a balanced feedline (open wire, twinlead, or twin-axial lines), place a jumper wire as
indicated on the back panel and connect the balanced feedline to the BALANCED LINE binding
posts. This antenna becomes ANTENNA 1. See “Antenna System Hints” on page 19.
4. A GROUND post is provided for an RF ground connection. See “Grounding Hints” on page 18.
5. Connect a 12 to 15 VDC power source to the input jack labeled POWER.
SWR/Wattmeter
The backlit cross-needle meter measures forward power,
reflected power, and SWR, and operates whenever the tuner is
powered on. Forward power up to 300 watts is displayed on the
left-hand FORWARD meter scale. Reflected power up to 60
watts is read on the right-hand REFLECTED meter scale. For
low-power tuning, meter ranges of 30 watts forward and 6 watts
reflected are available. Divide the readings on these scales by
ten when in the low power meter range.
0
10
30
50
100
200
300
0
5
20
40
60
8
5.0
3.0 2.0
1.5
1.2
Hi x1
Lo x.1
400-3083
1
10
Figure 6. SWR/Wattmeter.

MFJ-993 IntelliTuner Automatic Antenna Tuner Instruction Manual
©2003-2004 MFJ Enterprises, Inc.
9
To toggle between the high and low meter ranges, press the [TUNE] and [L-DN] buttons simultaneously.
The forward needle will read “300” for high range and “30” for low range until the buttons are released.
On the main LCD screen, in the high range a small dot appears in the lower right corner of the screen. No
dot appears in the low range. One beep indicates high range is selected; two beeps indicate low range is
selected. Refer to Figure 10 for the on-screen Meter Range indicator.
The meter can be set to auto range. Auto range automatically sets the meter scales according to the input
RF power to the tuner. Forward power greater than 30 watts or reflected power greater than six watts
automatically sets the meter to the high power range. Forward power less than 25 watts and reflected
power less than four watts automatically set the meter to the low power range. To toggle auto range on
and off, press the [TUNE] and [C-DN] buttons simultaneously. The reflected needle will read “60” for
auto range ON and “5” for auto range OFF. When auto range is on, a two-dot vertical segment appears in
the lower right corner of the screen. One beep indicates auto range on and two beeps indicate off. Refer
to Figure 10 for the on-screen Auto Range indicator.
The SWR is read from the eight red SWR curves that range from
1.0 to infinity. The SWR is measured by observing the point
where the forward and reflected power needles cross on the red
curved scales across the center of the meter. No cumbersome or
time-consuming SWR sensitivity adjustments are required with
this meter. Figure 6 shows an SWR of approximately 2.0.
The meter also indicates various operational states of the tuner. Refer to “Meter Codes and Audible
Beeps” on page 16 for more details.
The MFJ-993 also includes an SWR bar meter and an aural SWR indicator, selectable by pressing [L-UP]
and [L-DN] buttons simultaneously. It also has bar meters for forward and reflected power.
The Menus
Main Mode Menus
The main mode menus show various tuner settings and status. There are four main mode menus arranged
in a “wrap-around” structure. When powered on, tuner operation starts with the main menu that was last
used. Within each main menu, press the [MODE] button briefly to view the next main menu. Press and
hold the [MODE] button for two seconds to enter the setup mode (see below). Various tuner indicators
are shown on all four main menus: Antenna 1/2, Memory, IntelliTuneTM, Auto/Semi, StickyTune, SWR
Beep, LC Limit, and Meter Range. Refer to Figures 9 and 10 for details on the displayed information.
Note: In sideband mode, the frequency readout on the tuner display jumps around to different
frequencies while transmitting and stops on another frequency when un-keyed. This is
normal and is a characteristic of sideband mode, because sideband signals jump up and
down in frequency.
Digital Wattmeter Menu
Shows the frequency, SWR, and forward and reflected power in watts.
reflected power
1forward power
reflected power
1forward power
SWR
+
=
−

MFJ-993 IntelliTuner Automatic Antenna Tuner Instruction Manual
©2003-2004 MFJ Enterprises, Inc.
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Power Bar Meter Menu
Shows the frequency, SWR, and bar meters for forward and reflected power. The top bar meter is the
forward power and the bottom bar meter is the reflected power. The numeric reading of forward power
appears at the end of the bar meters. A power scale is printed just below the display on the front panel.
Each power bar meter is consisted of 60 bar segments. Below 100 watts, each bar segment represents two
watts; above 100 watts, each bar segment represents 20 watts. The forward bar meter has a “peak hold”
feature. The peak meter hold function freezes the highest displayed bar segment of the forward power for
about one second, so that you can more easily read the meter. This function can be turned ON and OFF
in the Peak Hold setup mode.
0 255075100
Pwr 300
Figure 7. Power Bar Meter.
SWR Bar Meter Menu
Shows the frequency, SWR and SWR bar meter. A SWR scale is printed just below the display on the
front panel. The 15-segment SWR bar meter indicates SWR of 1.0, 1.1, 1.2, 1.3, 1.4, 1.5-1.6, 1.7-1.9,
2.0-2.4, 2.5-2.9, 3.0-3.9, 4.0-4.9, 5.0-9.9, 10.0-14.9, 15.0-19.9, and 20.0 to infinity.
11.2 1.5 235
SWR
Figure 8. SWR Bar Meter.
L-Network Menu
Shows the SWR and the configuration of the L-network matching circuit. The antenna symbol, on the
upper left corner, indicates the antenna side of the L-network. The capacitance value is displayed to the
left when it is on the antenna side and to the right when on the transmitter side. Inductance value is
shown in microhenries (µH) and capacitance value in picofarads (pF). See “Manual Tuning” on page 16.

MFJ-993 IntelliTuner Automatic Antenna Tuner Instruction Manual
©2003-2004 MFJ Enterprises, Inc.
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MODE BUTTON FLOW CHART
SETUP MODESMAIN MODES
For 2 sec.
MODE
For 2 sec.
MODE
T
ARGET SWR
A
UTO TUNE SWR
METER RANGE
MEMORY
IntelliTune
SWR BEEP
BEEP
PEAK HOLD
REFRESH
LC LIMIT
MODE
MODE
MODE
+
+
C-UP
L-UP
TUNE C-UP
L-UPTUNE
TUNE L-DN
TUNE C-DN
C-DN L-DN
L-DNL-UP
C-UP C-DN
Press + to switch the capacitor between the input and output side.
Press + to toggle the SWR Beep on and off.
Press + to bypass the antenna tuner.
Press + to cycle the Auto Tune SWR among 0.5, 1.0 and 1.5 above the target SWR.
Press + to toggle the Target SWR between 1.5 and 2.0.
Press + to toggle the Auto Range on and off.
Press + to toggle the Meter Range between 300 and 30 watts (disable Auto Range).
BUTTON ACTION
Press + to increase both capacitance and inductance.
C-UP L-UP
MODE
AUTO
ANT
C-UP
L-UP
C-DN
L-DN
TUNE
POWER
Press less than 0.5 second to bypass the tuner; press and hold for 0.5 to 2 seconds to start the
tuning process; press and hold for more than two seconds to toggle the StickyTune on and off.
Press in to select semi-automatic mode, out to select automatic mode.
Press to decrease inductance.
Press to increase inductance.
Press to decrease capacitance.
Press to increase capacitance.
Press to switch main modes and setup modes.
Press in to select antenna 2, out to select antenna 1.
Press in to turn power on, out to turn power off.
Digital
Wattmeter
Power
Bar Meter
SWR
Bar Meter
L-Network
MODE
14.100 MHz 1.1
FWD=100 REF=0.5
14.100 MHz 1.1
100
14.100 MHz 1.1
Press or to turn on
or increase setting.
C-UP L-UP
C-DN L-DN
Press or to turn off
or decrease setting.
0.00uH 1.1
0pF
(while in the main modes)
Figure 9. Mode Button Flow Chart and Button Action.

MFJ-993 IntelliTuner Automatic Antenna Tuner Instruction Manual
©2003-2004 MFJ Enterprises, Inc.
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Frequency
Indicators: Antenna, Memory, IntelliTune
Indicators: Auto/Semi, StickyTune
SWR
Forward power in watts
Reflected power in watts
Indicators: SWR Beep, LC Limit, Meter Range
Forward power bar meter
Reflected power bar meter
Forward power in watts
SWR bar meter
Antenna symbol (antenna side of L-network)
Inductance value
Capacitance value when on antenna side
Capacitance value when on transmitter side
Appears when Antenna 1 is selected
Appears when Antenna 2 is selected
Appears when Memory is ON
Appears when IntelliTune is ON
Appears when in Semi-Auto mode
Appears when StickyTune is ON
Appears when LC Limit is OFF
Appears when SWR Beep is ON
Appears when Meter Range is 300 watts
Appears when Auto Range is ON
25
16
17
18
19
20
21
22
23
24
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
21
20
22 23
24
25
16
18 19
17
18 19
Enlarged Views of Indicators
2 2
3 7
1 2 3 4
5 6 7
10
8
9
1 2 3 4
7
11
1 2 34
7
12 13
14 15
2 3 4
7
Figure 10. Main Mode Menus Display.

MFJ-993 IntelliTuner Automatic Antenna Tuner Instruction Manual
©2003-2004 MFJ Enterprises, Inc.
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Tuner Indicators
Various tuner indicators are shown on the main menus to indicate tuner status. Refer to Figure 10 for
locations of these indicators.
• Antenna: A small “1” appears to indicate antenna 1 is selected; a small “2” appears to indicate
antenna 2 is selected.
• Memory: When Memory is ON, a bar appears on top-left of the Antenna indicator.
• IntelliTune: When IntelliTuneTM is ON, a bar appears on top-right of the Antenna indicator.
• Auto/Semi: A small “S” appears to indicate semi-automatic mode; nothing appears to indicate
automatic mode.
• StickyTune: When StickyTune is ON, a bar appears on top of the Auto/Semi indicator.
• SWR Beep: When SWR Beep is ON, a musical note ♪appears.
• LC Limit: When LC Limit is OFF, a two-dot vertical bar segment appears on the upper left corner
of the SWR Beep indicator.
• Meter Range: When Auto Range is ON, a two-dot vertical bar segment appears on the lower right
corner of the SWR Beep indicator. Another dot appears on top of this bar segment when the meter
range is high, and no dot when the meter range is low.
Setup Mode Menus
The setup mode menus allow you to set up how the MFJ-993 works and behaves. There are ten setup
mode menus arranged in a “wrap-around” structure. To access these setup menus, press and hold the
[MODE] button for two seconds. The setup menu that will display is the one that was last used. When
finished, press the [MODE] button for two seconds to go back to the main mode for normal operation.
The tuner goes into protective bypass mode in the setup mode and restores the matching network after
exiting the setup mode. If no button is pressed for more than eight seconds, the tuner automatically exits
the setup mode, restores the matching network, and returns to the main mode.
To access the LC Limit setup menu from any setup menu, press and hold the [MODE] button and within
two seconds press both [C-UP] and [L-UP] buttons. This difficulty is built-in so the LC Limit is not
accidentally disabled. Notice the LC Limit is not saved into non-volatile memory and will revert back to
default ON when power is turned off.
Within each setup menu:
• Press the [MODE] button briefly to cycle through the setup menus; press and hold the [MODE]
button for two seconds to exit the setup mode and go back to the main mode.
• Press the [C-UP] or [L-UP] button to increase or turn on the setting for the current setup menu.
• Press the [C-DN] or [L-DN] button to decrease or turn off the setting for the current setup menu.
Target SWR Menu
Allows you to set the target SWR from 1.0 to 2.0. The tuning process will stop when a match with an
SWR less than or equal to the target SWR is found. Setting the target SWR lower than 1.5 may require
longer tuning times. The target SWR is shown on the initial display when the tuner is powered on.
Default is 1.5.

MFJ-993 IntelliTuner Automatic Antenna Tuner Instruction Manual
©2003-2004 MFJ Enterprises, Inc.
14
Shortcut: Press both [TUNE] and [C-UP] buttons simultaneously to toggle the target SWR between
1.5 and 2.0, which is indicated by the meter SWR scale. Refer to Table 2 for meter code.
Auto Tune SWR Menu
Allows you to set the SWR threshold in the range 0.5 to 1.5. In the automatic mode, the tuning process
will automatically start when the SWR is above the target SWR by this amount of SWR threshold. For
example, for target SWR of 1.5 and auto tune SWR of 1.0, the tuning process will start whenever the
SWR is above 2.5 (1.5 + 1.0) and there is at least 5 watts of RF power. Default is 1.0.
Shortcut: Press both [TUNE] and [L-UP] buttons simultaneously to cycle the auto tune SWR
among 0.5, 1.0 and 1.5. Refer to Table 2 for meter code.
Meter Range Menu
Allows you to select the meter scale range. In the 30 watts (low) range, the forward full scale is 30 watts
and the reflected full scale is 6 watts (divide the meter reading by 10). In the 300 watts (high) range, the
forward full scale is 300 watts and the reflected full scale is 60 watts. Auto range automatically sets the
meter scales according to the input RF power to the tuner. Forward power greater than 30 watts or
reflected power greater than six watts automatically sets the meter to the high power range. Forward
power less than 25 watts and reflected power less than four watts automatically set the meter to the low
power range. Refer to Figure 10 for the on-screen Meter Range indicators. Default is 300 watts range.
Shortcut: Press both [TUNE] and [C-DN] buttons simultaneously to toggle Auto Range on and off.
Press both [TUNE] and [L-DN] buttons simultaneously to toggle between 300 and 30
watts meter range and disable Auto Range. Refer to Table 2 for meter code.
Memory Menu
Turns the antenna memory on and off. The “memory resolution” is the width of frequency spectrum that
the tuner recognizes as being the same as a tuned frequency already in memory. The memory resolution
is approximately 0.1 percent of the lower frequency of each amateur band. For example, the memory
resolution on the 40-meter band (7000 to 7300 kHz) is 7 kHz; if the tuner has memorized a setting for
7050 kHz, it will automatically call up this setting for any frequency from 7047 to 7053 kHz. The
memory resolutons for the HF amateur bands 160 through 10 meters are:
Meter Frequency Range (kHz) Memory Resolution (kHz)
160 1800 – 2000 2
75/80 3500 – 4000 4
60 5330.5, 5346.5, 5366.5; 5371.5 and 5403.5 two memory locations
40 7000 – 7300 7
30 10100 – 10150 10
20 14000 – 14350 14
17 18068 – 18168 18
15 21000 – 21450 21
12 24890 – 24990 25
10 28000 – 29700 28
Table 1. Memory Resolution.